Field of the Invention
The present invention relates to crushing machinery and, specifically, to an impact crusher and curtain adjustment system for manually or automatically adjusting crusher settings to control product size produced by the crusher.
Description of Related Art
Crushing machinery is used to reduce large rocks, concrete, asphalt, and the like into smaller rocks, gravel, or rock dust for use in construction and building industries. Hard rock generally refers to rock materials that are hard, tough, abrasive, and have low friability, such as materials produced from shot rock or gravel quarries. As such, the crushing machinery is often provided in remote locations, such as quarries or construction sites.
One type of crushing machinery well-suited for reducing the size of hard materials is an impact crusher, such as an Andreas-style crusher, New Holland-style crusher, or Hammer Mill-style crusher. Impact crushers have been known for many years and are commercially available from a number of manufacturers including the Assignee of the present application, McLanahan Corporation of Hollidaysburg, Pa. An impact crusher includes a body or housing defining a crushing chamber and having a rotor mounted therein. The rotor is configured to strike feed material, such as rocks or other hard materials that enter the crushing chamber through a feed opening of the housing. The rotor includes a plurality of arms, referred to as hammers or blow bars, extending radially therefrom, which serve as the primary impact devices for breaking down feed material in the crushing chamber. A body, referred to as a curtain, anvil, apron, or breaker plate having an impact surface against which material present in the crushing chamber can be directed during operation of the crusher, extends into the crushing chamber a predetermined and adjustable distance. The impact surface of the body can be angled toward the swept area or hammer circle defined by the blow bars or hammers. The distance between the curtain and swept area or hammer circle determines the maximum grade of material that can pass through the crushing chamber. Exemplary impact crushers are disclosed in U.S. Pat. No. 7,293,725 to Moriya et al. and U.S. Pat. No. 8,033,489 to Boast.
Known impact crushers can include a number of different types of mechanisms, such as hydraulic jacks, mechanical shims, and locking mechanisms, for adjusting the position and orientation of the curtains or aprons. In most cases, the mechanisms are configured to adjust the curtain or apron position when the rotor is stationary and when the main crusher drive mechanism is powered down. Accordingly, curtain position is usually adjusted prior to beginning a crushing operation. Many known crushers also do not include monitoring or operating systems that are capable of monitoring operation of the crusher and making adjustments necessitated by wear to crusher components while the apparatus is in use.
For these reasons, new systems for adjusting operating settings and monitoring operation of impact crushers are needed. More specifically, there is a need for an improved adjusting system that is capable of determining the position of the curtain or apron and, when necessary, adjusting the position of the curtain or apron to change the product size produced or to reduce wear to crushing components. The impact crusher and adjusting system described herein are intended to address these issues.